AND SOLUTIONS RATED A+
✔✔As the potentials of the ___ sites polarize
toward the potentials of the ____ sites, corrosion current is ____.
A) anodic, cathodic, increase
B) cathodic, anodic, reduced
C) cathodic, anodic, increase
D) anodic, cathodic, decrease - ✔✔b
✔✔Polarization occurs in a step-like manner with the more
____ or ____ sites polarizing first.
A) positive, anodic
B) positive, cathodic
C) negative, anodic
D) negative, cathodic - ✔✔b
✔✔To mitigate corrosion, all existing cathode sites must be electronegatively
polarized to a potential ____ to the open circuit potential of the most ___
____ potential existing on the structure.
A) equal, inactive, cathode
B) unequal, active, anode
C) unequal, inactive, cathode
D) equal, active, anode - ✔✔d
✔✔Polarization of the ____ to the ____ potential of the anodes is the true criterion for
eliminating corrosion.
A) cathodes, closed circuit
B) anodes, closed circuit
C) cathodes, open circuit
D) anodes, open circuit - ✔✔c
✔✔Bare Pipe:
What is the current required to protect an uncoated 30.48 cm (12 in.) diameter
steel pipeline 1,524 m (5,000 ft) in length that is buried in soil with a resistivity
of 10,000 Ω-cm?
Assume experience has shown that adequate levels of
cathodic protection can be achieved from 10.76 mA/m 2 (1 mA/ ft 2 ) of bare
surface area.
,A) 16.8A
B) 15.7A
C) 14.7A
D 13.8A - ✔✔b
✔✔Coated Pipe:
What is the current required to protect an uncoated 30.48 cm (12 in.) diameter
steel pipeline 1,524 m (5,000 ft) in length that is buried in soil with a resistivity
of 10,000 Ω-cm?
Assume that 5 percent of the pipe contains holidays or defects in the coating
A)0.8538A
B) 1.785A
C) 0.785A
D) 2.754A - ✔✔c
✔✔For a cathodic protection system, a(n) ____ in the cathodic
polarization is desired to _____ the current requirement for the structure.
A) decrease, increase
B) increase, increase
C) decrease, decrease
D) increase, decrease - ✔✔d
✔✔The current required for cathodic protection generally is _____ in low pH
(acids) than in high pH (basic) and neutral environments.
A) lower
B) greater - ✔✔b
✔✔What two phenomena account for the increase in CP current requirement in low pH
environments?
A) shift in the negative directions of the structure's open circuit cathode potential / a
flattening of cathodic polarization curve for the structure
B) shift in the positive direction of the structure's open circuit cathode potential / a
flattening of cathodic polarization curve for the structure - ✔✔b
✔✔The structure's cathodic polarization slope is flattened with _____ acidity
because of the increased concentration of reducible _____ ion
,A) increasing, hydrogen
B) decreasing, hydrogen
C) increasing, OH-
D) decreasing, OH- - ✔✔a
✔✔True or False (t or f)
The pH of an electrolyte (soil or water) is USUALLY a neutral 7 - ✔✔f
✔✔_______ (an acid salt) used as a fertilizer tends to decrease pH of the soil.
A) calcium sulfate
B) ammonium sulfate
C) carbon sulfate
D) magnesium sulfate - ✔✔b
✔✔_____ in temperature has a depolarizing effect
A) increase
B) decrease - ✔✔a
✔✔When the rate of reduction reaction is ____, it ____ the level of polarization and
_____ the cathodic protection current requirement
A) increased, increases, increases
B) increased, decreases, decreases
C) increased, decreases, increases
D) decreased, increases, decreases
E) decreased, decreases, decreases - ✔✔c
✔✔Increased temperature will ____ ionization
A) increase
B) decrease - ✔✔a
✔✔As ionization _____,
the electrolyte's conductivity _____, which _____ corrosion current and
the amount of cathodic protection current required for adequate protection.
A) increases, increases, increases
B) increases, decreases, decreases
C) increases, decreases, increases
D) decreases, increases, decreases
E) decreases, decreases, decreases - ✔✔a
, ✔✔Oxygen or other oxidizers ____ the current requirements as a result of
flattening the cathodic polarization slope
A) increase
B) decrease - ✔✔a
✔✔True or False (t or f)
structures in well aerated soils, such as sand and gravel, require
more cathodic protection current than structures surrounded by relatively
deaerated soils, such as clay. - ✔✔t
✔✔A(n) _____ in the relative movement between the electrolyte and the structure
causes a(n) _____ in current requirement
A) increase, decrease
B) increase, increase
C) decrease, increase
D) decrease, decrease - ✔✔b
✔✔True or False (t or f)
a ship under way requires less cathodic protection current than a
ship at rest - ✔✔f
✔✔To reduce the residual corrosion current to zero, cathodic protection current
must be _______
A) disproportionately increased
B) disproportionately decreased
C) proportionately increased
D) proportionately decreased - ✔✔a
✔✔The relationship between applied cathodic protection current and corrosion rate is
____
A) proportional
B) disproportional
C) logarithmic - ✔✔c
✔✔In regards to amphoteric metals:
The formation of ____ ions at the cathode causes the pH of the electrolyte next to
the cathode to become ____.